MD 43 begins at a partial interchange with I-695 (Baltimore Beltway) near Parkville that includes ramps from eastbound I-695 to eastbound MD 43 and from westbound MD 43 to westbound I-695. The state highway heads east as a four-lane divided
limited-access highway through the forested valley of Whitemarsh Run. As MD 43 passes through the community of
Fullerton, the highway has intersections with county-maintained Walther Boulevard and a pair of two-way
quadrant ramps that connect the boulevard with either direction of
US 1 (Belair Road), under which MD 43 passes between the pair of ramps. The state highway continues east into the planned community of White Marsh where the highway has intersections with Perry Hall Boulevard and Honeygo Boulevard, which serve
White Marsh Town Center and its centerpiece,
White Marsh Mall. East of the town center, MD 43 veers away from Whitemarsh Run and meets I-95 (John F. Kennedy Memorial Highway) at an interchange; this interchange has full access to I-95 along with access to the southbound direction of the I-95 Express Lanes and from the northbound direction of the I-95 Express Lanes. Past I-95, the route has a partial interchange with
MD 7 (Philadelphia Road). The state highway continues east over
CSX's
Philadelphia Subdivision railroad line and US 40 (Pulaski Highway). The US 40 interchange includes a two-way quadrant ramp between the two highways and a direct ramp from southbound US 40 to westbound MD 43. East of US 40, the state highway crosses over Whitemarsh Run, which heads north to its mouth at the tidal Bird River, itself a tributary of the
Gunpowder River. MD 43 curves southeast through a forested area with scattered industrial parks, where the highway crosses over Bird River Road and Windlass Run and intersects Crossroads Circle. The state highway continues southwest into Middle River, crossing over
Amtrak's
Northeast Corridor railroad line before reaching its eastern terminus at MD 150 (Eastern Boulevard) just east of the
Martin State Airport station on
MARC's
Penn Line and
Martin State Airport. MD 43 is a part of the
National Highway System as a principal arterial for its entire length. ==History==